Blockchain Security Training Fundamentals of Blockchain Security 3

Question 1

In public-key cryptography used by blockchains, which key is shared openly?

Accepted Answer

The public key

Answer

The public key (or derived address) is shared so others can verify signatures and send funds.

Question 2

What is a Sybil attack in a blockchain network?

Accepted Answer

Flooding the network with fake identities to gain disproportionate influence

Answer

A Sybil attack uses many fake nodes or identities to subvert reputation or consensus systems.

Question 3

How does Proof of Work deter attacks on a blockchain?

Accepted Answer

By requiring attackers to expend large computational resources

Answer

PoW makes attacks economically costly because rewriting history requires enormous computing power.

Question 4

What is the main security trade-off of storing assets in a hot wallet?

Accepted Answer

It is internet-connected and more exposed to remote attacks

Answer

Hot wallets stay online for convenience but their connectivity increases exposure to hacking.

Question 5

Which of the following is a key benefit of a cold storage wallet?

Accepted Answer

Private keys kept offline, away from network attacks

Answer

Cold storage keeps keys offline, drastically reducing the attack surface for remote theft.

Blockchain Practice Test